I love Thumbjam and have used the app for years. I've got a problem however with using a MIDI keyboard with Thumbjam. When I play a note on my MIDI keyboard (connected via the iPad USB Camera Connection Kit), the note played is not the one that sounds out in TJ. It always seems to be a semitone higher.

For example: I play an E and it plays F , meaning that everything I play I have to drop a semitone to get it sounding correct. This problem extends to both Thumbjam and within Cubasis via Inter-App-Audio.

Check in the Prefs->MIDI Control page for the MIDI Input Transpose setting and make sure it is set to zero. Also be sure that Scale Lock is turned OFF (this is a feature that turns all the white keys into the currently selected scale, which can be cool, but not what you usually want).